Excluding Matches With Regular Expressions

One easy way to exclude text from a match is negative lookbehind:

w+b(?<!bfox)  

But not all regex flavors support negative lookbehind. And those that do typically have severe restrictions on the lookbehind, eg, it must be a simple fixed-length expression. To avoid incompatibility, we can restate our solution using negative lookahead:

(?!foxb)bw+

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